Mat2Eul:

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   Converts an orthonormal transformation matrix into 3-2-1 Euler angles.
   Uses the input e(1) for e(1) near the singularity.

   Since version 1.
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   Form:
   e = Mat2Eul( m, e )	
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   ------
   Inputs
   ------
   m		(3,3)  Orthonormal transformation matrix
   e		(3,1)  Euler angles

   -------
   Outputs
   -------
   e		(3,1)  Euler angles

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